Four-stage hospital-type filtration that effectively cleans air in small spaces. The Smart Sensor detects air quality and automatically adjusts the fan speed to keep your air purified. A True HEPA filter with antimicrobial treatment safely removes 99.97% of airborne particles as small as 0.3 microns, including allergens, viruses, and cigarette smoke. Proven effective at capturing the airborne flu virus. Carbon filter removes odors. Certified asthma & allergy friendly™ by the Asthma and Allergy Foundation of America. The air purifier also includes the Aera+™ Mode for allergy and cold/flu seasons and features ultra-quiet operation.